This invention relates to a vacuum processing apparatus for surface treatment of a substrate in vacuum.
Surface treatment apparatuses using plasma have been publicly known as vacuum processing apparatuses of this kind. Particularly, dry etching apparatuses using reactive gas plasma have been widely used in semiconductor element production.
Apparatuses shown in FIGS. 1-3 have been widely used as the dry etching apparatuses. The apparatus shown in FIG. 1 is of a batch processing type wherein every time a substrate is loaded or unloaded, a processing chamber 1 is exposed to the atmosphere and after the substrate 18 is loaded, the processing chamber is evacuated and the vacuum processing is effected.
The apparatus shown in FIG. 2 comprises a processing chamber 1, a load-lock chamber 2a having a valve 51a and a valve 51b connecting the chambers 1 and 2a, and a further unload-lock chamber 2b having a valve 51c connecting the chambers 1 and 2b and a valve 51d. Substrates 18 arranged in the atmosphere are fed one by one from a substrate holder 3 through the opened valve 51a into the load-lock chamber 2a. The substrate 18 is further fed from the load-lock chamber 2a through the valve 51b into the processing chamber 1 in which the substrate 18 is processed in a predetermined manner. Thereafter, the processed substrate 18 is fed through the valve 51c into the unload-lock chamber 2b and further fed through the valve 51d into a substrate holder 3 in the atmosphere. This apparatus is a processing apparatus having so-called vacuum-tight mechanisms.
With the apparatus shown in FIG. 3, substrates 18 together with a substrate holder 3 accommodating the substrates are introduced into a load-lock chamber 2a having a large volume. The substrates 18 are transferred one by one through a substrate transferring chamber 4 arranged between a processing chamber 1 and the load-lock chamber 2a into the processing chamber 1 in which the substrate 18 is processed. Then, the substrate 18 is restored again through the substrate transferring chamber 4 into a unload-lock chamber 2b having a large volume and having a substrate holder 3. Thereafter, the substrate is taken out of the unload-lock chamber 2b into the atmosphere. Reference numerals 51e and 51i denote valves.
However, these apparatuses have various disadvantages. With the apparatus shown in FIG. 1, when the substrate is fed into or removed from the processing chamber 1, the air enters the processing chamber so that moisture (H.sub.2 O) in the air will deposit on inner walls of the processing chamber 1. Therefore, in the stage of processing the substrate in the processing chamber 1 kept evacuated, the deposited gas (almost as H.sub.2 O) is evacuated which considerably detrimentally affects the reproducibility of etching performance.
In the apparatus shown in FIG. 2, when the substrate 18 is fed into or removed from the processing chamber 1, such a movement of the substrate is effected through the load-lock chamber 2a and the unload-lock chamber 2b so that the air is prevented from entering the processing chamber 1 to an appropriate extent in comparison with the apparatus shown in FIG. 1. When one cycle is effected in a short period of time or 2-3 minutes, which consists of vacuum processing of substrate in the vacuum chamber 1, removing it from the chamber and introducing a next substrate into the chamber, the air-tightness of the vacuum chamber is not enough because the inlet and outlet of the chamber 1 for the substrates are separately provided. Therefore, there is a detrimental affect of deposited gases similar to that in the apparatus shown in FIG. 1 to make it impossible to accomplish the stable substrate processing (etching). Moreover, another problem often arises in that when a substrate made of aluminium is taken out of the processing chamber into the atmosphere after it has been etched, the moisture (H.sub.2 O) in the atmosphere is deposited on the substrate so that it causes corrosion of aluminium patterns on the substrate, thereby considerably lowering the yield rate of the products.
With these apparatuses shown in FIGS. 1-3, moreover, it is necessary to change basic members such as parts in the processing chamber 1 and the construction of the chamber itself in the event that the processing mode of substrate is changed.
In this case, transference mechanisms (not shown) and the processing chamber 1 need to be modified in a complicated manner particularly with the apparatuses shown in FIGS. 2 and 3 wherein the load-lock chamber 2a and the unload-lock chamber 2b or the vacuum transferring chamber 4 exclusively provided adjacent to the processing chamber 1 and the transference mechanisms are distributed in the respective chambers. In order to avoid such complicated modifications, vacuum processing apparatuses tend generally to become exclusive apparatuses according to applications. On the other hand, this is a great handicap for development of multipurpose apparatuses.